Steps

Sequential Function Chart (SFC) programs contain initial steps and steps. Initial steps express the initial situation of an SFC program. Whereas, steps are placed throughout an SFC program. An SFC program must contain at least one initial step. Initial steps are double bordered. Initial steps and steps are referenced by a name, written in their square symbol. This information is the level 1 of the step.

An initial step has a double bordered graphic symbol.

Initial Step

A step is represented by a single square.

Step

At run time, a token indicates that the step is active. For initial steps, a token is automatically placed in each when the program is started.

Active Step

Inactive Step

Steps have attributes. These can be used in any of the other languages.

StepName.x activity of the Step (Boolean value)

StepName.t activation duration of the Step (time value)

(where StepName is the name of the step)

Activity of a step is an attribute of a step which is activated by an SFC token.

For SFC function blocks, when reading a child active step or duration from a parent:

ChildName.__S1.x activity of the Step (Boolean value)

ChildName.__S1.t activation duration of the Step (time value)

(where ChildName is the name of the child. Note that S1 is preceded by two underscore (_)characters)

Task	Procedure
Insert an initial step	From the Toolbox , drag the Initial Step element into the language container.
Insert a step	From the Toolbox , drag the step element into the language container.
Renumber steps and transitions	Renumbering ignores steps and transitions using a naming convention other than the default Sn for steps and Tn for transitions. Open the SFC program for which to renumber the steps and transitions. From the Tools menu, point to Multi-language Editor , and then click Renumber Steps and Transitions .

Coding Action Blocks for Steps

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